Resetting means for number wheels



W. W. HOFFMANN RESETTING MEANS FOR NUMBER WHEELS Nov. 4, 1958 2 Sheets-Sheet 1 Filed June 9, 1955 1' N 1/5 N7 02 We: Zier W Jig/[mama flztorngy Nov. 4, 1958 w. w. HOFFMANN RESETTING MEANS FOR NUMBER WHEELS Filed June 9, 1955 2 Sheets-Sheet 2 United States Patent RESETTIN G MEANS FOR NUMBER WHEELS Walter W. Hotfmann, Waukesha County, Wis., assignor to'Durant Manufacturing Co., Milwaukee, Wis., a corporation of Wisconsin Application June 9, 1955, Serial N 0. 514,175

4 Claims. (Cl. 235-144) This invention relates to improvements in resetting means for number wheels and to the method of installing such means in said wheels.

The object of this invention is to provide resetting means which is: inexpensive to manufacture and assemble; light and strong; quiet and of low frictional resistance in operation; accurate in attaining reset position; and easy to hold to close tolerances in the manufacture thereof.

This object is obtained by reset means which consists of a single spring fixedly mounted in a cavity in the number wheel, and having one free end extending into the bore of such wheel to ride on the reset shaft and engage the reset groove in such shaft during resetting. The spring may have a curved section seated snugly in a pocket in such cavity and a holding section held by swedging parts of the material of the wheel tightly over such holding section. Thus the spring performs the dual function of a spring and a pawl. By eliminating the pawl as a separate element, manufacturing expenses are lessened, dimensional errors minimized with consequent greater accuracy, assembly problems solved, and other benefits obtained as hereinafter pointed out.

The features of the invention which are considered new and useful and, therefore, patentable are set forth in the claims below. The details of an embodiment of the invention can best be understood from the following specification and the drawings, in which:

Fig. 1 is a view in front elevation of a number wheel having resetting means embodying the present invention, said wheel shown mounted on a reset shaft;

Fig. 2 is a sectional view taken on the line 22 of Fig. 3 showing the reset spring outside of the spring cavity with the reset shaft removed;

Fig. 3 is a view in front elevation of the reset wheel of Fig. 1 with the reset shaft removed and with the reset spring temporarily held in the spring cavity prior to swedging and anchoring the reset spring;

Fig. 4 is a sectional view taken on the line 44 of Fig. 1 showing the swedged anchoring of the reset spring;

Fig. 5 is a view in rear elevation of the reset wheel of Fig. l; and

' Fig. 6 is a diagrammatic view of the mandrel and die for swedging and anchoring the reset spring.

Number wheels each embodying this invention are mounted in bank on a reset shaft to form a counter of the resettable type. Each wheel drives an adjacent wheel through transfer pinions during counting rotation. When the reset shaft is rotated in the same direction as the counting rotation, all of the number wheels are reset to zero. Referring to the drawings in detail, the number wheel 10 is preferably formed from plastic such as nylon (polyamide resin) by a moulding operation. It has a central hub 12 extending from both sides of a web. The Wheel is rotatably mounted on a reset shaft 13 (shown only in Fig. 1) which passes through a bore 14 in such hub. The reset shaft 13 has an elongated groove 15 which provides a shoulder engageable by the ends of the reset spring, upon the rotation of the shaft counter-clockwise as viewed in Fig. l. The number wheel 10 has the usual: locking disc 17; two-tooth transfer segment 16; and internal notches 18 (see Fig. 5) engageable by pawls on a gear wheel (not shown). A rib or bar 20 extending diametrically of the wheel cooperates with a rim 30 to form a spring cavity 23. The rib 20 also provides a flat rest 22 for the legs of the reset spring. This fiat rest extends through the hub 12 to form an opening between the spring cavity and the bore so that an end of the reset spring may extend into the bore 30 for proper engagement with the reset shaft. In the spring cavity there is a holding boss 24 projecting from the bottom thereof. This boss has a flat outer face to engage, properly locate and support the reset spring. At opposite ends, the spring cavity has curved pockets 26 for snugly receiving the curved portions of the reset spring. A reset spring 28, having two legs and a flat side joined by curved ends, is seated in the spring cavity 23 with such curved ends firmly held in non-binding bearing relationship in the pockets 26. When the spring 28 is'inserted as shown in Fig. 3, but not anchored, it will be temporarily frictionally held in such proper place for. easy handling prior to anchoring or swedging.

The reset spring 28 is anchored in fixed place by swedging (as hereinafter described) a portion 32 from the rim 30 and a portion 33 of the boss 24 over the fiat side of such spring. An end 34 of the spring 28 extends from the spring cavity 23-into the bore 14 so as to rest upon the reset shaft 13 and engage with the shoulder in the elongated groove 15 to transfer counterclockwise rotation of the reset shaft 13 to the wheel 10 while permitting such wheel to move in counter-clockwise rotation relative to such shaft. Thus the reset spring 28 performs the double function of providing a detent and a spring for the detent. The leg of the spring is long enough to readily flex and press against the reset shaft 13 with the least amount of friction. However, the end 34 will always snap into engagement with the groove 15. During resetting of the wheel, the driving force exerted on the end 34 of the reset spring is transmitted along such spring causing the curved section to be gripped by the pockets 26. Hence, it is preferable to have such pockets oppositely placed. Two oppositely positioned pockets make it possible to frictionally hold the spring in proper place during the swedging. If only one pocket is used it is advisable to have a shoulder-like abutment in the boss 24 for the end of the spring opposite the end 34. By using a single spring for such dual function, considerable expense is eliminated and dimensional inaccuracies lessened, thus assuring that upon reset the zeroes (not shown) will be properly alined together in the counter window.

The swedging to anchor the reset spring 28 is accomplished by mounting in a vice 36, a mandrel 38 the outer wall of which is gear-shaped to nest snugly in the internal notches 18 of the wheel. The mandrel is tilted to approximated 10 from vertical for the purpose hereinafter explained. The wheel 10 is seated on the mandrel and a die 40, heated by a heating element 46, is brought into engagement with the wheel so that the inner face of tooth 42 hits against the inside edge of the holding boss 24 and the tooth 44 sheers a portion of material from the rim 30 and forces it against and over the fiat of spring 28. Because of the tilt of the mandrel and the wheel, the tooth 44 will perform its function first and thus force the spring 28 toward and hold it against the outer face of the boss 24. This accurately positions the spring. The tooth 42 performs its function and the anchoring is complete. The die 40 is brought down until the tooth 42 hits the bottom of the spring cavity 23. It is then instantly withdrawn to permit quick setting of the swedged material in the shape shown in Fig. 4. The steps of seating the spring and then swedging it can be performed at high speed and with close tolerance, thus insuring a high standardization. Furthermore, after such assembly the wheel is a sub-assembly which can be readily stored and handled prior to assembly with a gear wheel. This could not be done with the conventional spring and separate detent.

I claim:

1. In a number wheel, a hub having a bore, a reset spring cavity in said wheel having an opening to said bore, said cavity having walls forming oppositely facing pockets, a boss in said cavity adjacent a well thereof, and a reset spring in said cavity having curved sections seated in said pockets and a leg extending through said Opening with an end in said bore, a portion of said spring spaced'from said end being adjacent the side of said boss opposite said wall, a part of said boss and said wall overlying and engaging said portion to rigidly anchor said spring.

' 2. In a number wheel, a bore adapted to receive a reset shaft, a side opening to said bore, a reset spring having oppositely related curved portions, a connecting portion anchored in said wheel and a free end projecting into said opening and biased toward said bore and into said side opening to cooperate with a reset shaft during resetting, and oppositely opening pockets on said wheel, said curved portions fitting snugly in said pockets to ac: curately locate the free end of said spring in said openmg. l

3. In the number wheel as claimed in claim 2, means for anchoring said spring comprising a boss on said a reset spring cavity in said wheel having a flat portion providing a flat rest for the leg of a reset spring, said cavity having an opening to said bore at the radially inner end of said flat rest portion, said cavity having at the radially outer end of said flat portion a part angling with respect to said flat portion to provide a first locating abutment for the curved section of a reset spring, said cavity having a second locating abutment for the holding section of a reset spring spaced from and facing toward said first locating abutment, a reset spring in said cavity having a leg resting on said flat rest and extending through said opening and into said bore to cooperate with a reset shaft, said spring having a curved section at the radially outer end of said leg seated against said first locating abutment, said spring having a holding section extending from said curved section and resting against said second locating abutment, and a boss in said cavity integral with said wheel and engaging a side of said holding section of said spring, part of said boss overlying and tightly gripping said holding section to permanently hold said spring in said cavity.

References Cited in the file of this patent UNITED STATES PATENTS 2,444,570 Lawrence et a1. July 6, 1948 2,486,043 Lcfgren Oct. 25, 1949 2,547,751 Harada Apr. 3, 1951 2,737,345 Harada Mar. 6, 1956 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2,858,986 November 4, 1958 Walter w. Hoffmann It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below,

Column-3, line 14, for F'adjacent a Well read adjacent a Well (SEAL) KARL AXLINE Attest:

ROBERT C WATSON Comnissioner of Patents Attesting- Officer KARL s, AXLINE Attesting- Officer UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noa 2,858,986 I November 4, 1958 Walter W. Hoffmaxm It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected belowa Column 3, line 14, for f'adjacent a Well" read adjacent a Wall Signed and sealed this 24th day of February 1959.

Attest:

ROBERT C. WATSQN Commissioner of Patents 

